This is the one that I use:
.backlink-pane .search-result-file-matched-text,
.workspace-leaf-content[data-type="search"] .search-result-file-matched-text,
.internal-query .search-result-file-matched-text {
background: none;
color: var(--text-accent);
}
It removes the background and gives the text your accent colour, which is what I prefer.
The snippet is for the global search, inline search queries & the backlinks pane, if you only want this to apply to the global search then just remove the other two selectors:
.workspace-leaf-content[data-type="search"] .search-result-file-matched-text {
background: none;
color: var(--text-accent);
}
I hope this helps.